Description:
A simple explanation of how a transistor works. Most introductory textbooks do a very poor job of explaining the details of how transistors work. First they assume that the Base current is somehow controlling the Collector current, then they try to explain how one current can affect another. These explanations always fail because Bipolar transistors, like FETs, are voltage-controlled devices. One current doesn't affect another. Instead, the Base-Emitter voltage controls the thickness of an insulating "depletion layer" which lies in the path of both the Collector current and the Base current.